Pyruvate Kinase M2 Regulates Gene Transcription by Acting as a Protein Kinase

Department of Biology, Georgia State University, Atlanta, GA 30303, USA.
Molecular cell (Impact Factor: 14.46). 02/2012; 45(5):598-609. DOI: 10.1016/j.molcel.2012.01.001
Source: PubMed

ABSTRACT Pyruvate kinase isoform M2 (PKM2) is a glycolysis enzyme catalyzing conversion of phosphoenolpyruvate (PEP) to pyruvate by transferring a phosphate from PEP to ADP. We report here that PKM2 localizes to the cell nucleus. The levels of nuclear PKM2 correlate with cell proliferation. PKM2 activates transcription of MEK5 by phosphorylating stat3 at Y705. In vitro phosphorylation assays show that PKM2 is a protein kinase using PEP as a phosphate donor. ADP competes with the protein substrate binding, indicating that the substrate may bind to the ADP site of PKM2. Our experiments suggest that PKM2 dimer is an active protein kinase, while the tetramer is an active pyruvate kinase. Expression of a PKM2 mutant that exists as a dimer promotes cell proliferation, indicating that protein kinase activity of PKM2 plays a role in promoting cell proliferation. Our study reveals an important link between metabolism alteration and gene expression during tumor transformation and progression.

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Available from: Xueliang Gao, Feb 03, 2015
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    • "For instance, the M2 isoform of pyruvate kinase (PKM2), which forms a tetramer in the cytosol, is the final key enzyme in aerobic glycolysis. However , PKM2 can translocate into the nucleus to act as a protein kinase in its dimeric form and phosphorylate signal transducer and activator of transcription 3 (Gao et al., 2012) or to directly interact with HIF1-a to promote downstream target transactivation (Luo et al., 2011). The possibilities of different subcellular localizations, conformations, and nonenzymatic functions of ME are worthy of further investigation. "
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    ABSTRACT: Cutaneous melanoma is the most life-threatening neoplasm of the skin, accounting for most skin cancer deaths. Accumulating evidence suggests that targeting metabolism is an appealing strategy for melanoma therapy. Mitochondrial NAD(P)(+)-dependent malic enzyme (ME2), an oxidative decarboxylase, was evaluated for its biological significance in cutaneous melanoma progression. ME2 mRNA and protein expression significantly increased during melanoma progression, as evidenced by Gene Expression Omnibus (GEO) analysis and immunohistochemistry on clinically annotated tissue microarrays, respectively. In addition, ME2 knockdown attenuated melanoma cell proliferation in vitro. ME2 ablation resulted in reduced cellular ATP levels and elevated cellular ROS production, which activated the AMP-activated protein kinase (AMPK) pathway and inhibited acetyl-CoA carboxylase (ACC). Furthermore, ME2 expression was associated to cell migration and invasion. ME2 knockdown decreased anchorage-independent growth in vitro and tumor cell growth in vivo. These results suggested that ME2 might be an important factor in melanoma progression and a novel biomarker of invasion.Journal of Investigative Dermatology accepted article preview online, 09 September 2014. doi:10.1038/jid.2014.385.
    Journal of Investigative Dermatology 09/2014; 135(3). DOI:10.1038/jid.2014.385 · 6.37 Impact Factor
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    • "Given the unabated rate of progress since its discovery more than 30 years ago, we are certainly in for more surprises and insights, and undoubtedly, this will require the development of new technologies. It seems unlikely that additional dedicated TKs will be identified, but the recent report that PKM2 can phosphorylate STAT3 on Tyr705 (Gao et al. 2012) means that other enzymes that use ATP, or another substrate with an energy-rich phosphate, might also moonlight as TKs under special circumstances . Likewise, additional P.Tyr phosphatase activities may emerge; a recent example is STS- 1, a member of the histidine phosphatase family that has been reported to be a P.Tyr phosphatase (Mikhailik et al. 2007). "
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    ABSTRACT: Tyrosine phosphorylation of proteins was discovered in 1979, but this posttranslational modification had been "invented" by evolution more than a billion years ago in single-celled eukaryotic organisms that were the antecedents of the first multicellular animals. Because sophisticated cell-cell communication is a sine qua non for the existence of multicellular organisms, the development of cell-surface receptor systems that use tyrosine phosphorylation for transmembrane signal transduction and intracellular signaling seems likely to have been a crucial event in the evolution of metazoans. Like all types of protein phosphorylation, tyrosine phosphorylation serves to regulate proteins in multiple ways, including causing electrostatic repulsion and inducing allosteric transitions, but the most important function of phosphotyrosine (P.Tyr) is to serve as a docking site that promotes a specific interaction between a tyrosine phosphorylated protein and another protein that contains a P.Tyr-binding domain, such as an SH2 or PTB domain. Such docking interactions are essential for signal transduction downstream from receptor tyrosine kinases (RTKs) on the cell surface, which are activated on binding a cognate extracellular ligand, and, as a consequence, elicit specific cellular outcomes.
    Cold Spring Harbor perspectives in biology 05/2014; 6(5). DOI:10.1101/cshperspect.a020644 · 8.23 Impact Factor
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    • "Due to the observed role of SAICAR in the nuclear localization of PKM2, we decided to examine the effect of SAICAR on the constitutively nuclear mutant PKM2 R399E (Gao et al. 2012; Supplementary Figure S3). Recombinant PKM2 R399E was purified from E. coli and the kinetic parameters measured. "
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    ABSTRACT: Abnormal metabolism and sustained proliferation are hallmarks of cancer. Pyruvate kinase M2 (PKM2) is a metabolic enzyme that plays important roles in both processes. Recently, PKM2 was shown to have protein kinase activity phosphorylating histone H3 and promoting cancer cell proliferation. However, the mechanism and extent of this protein kinase in cancer cells remain unclear. Here, we report that binding of succinyl-5-aminoimidazole-4-carboxamide-1-ribose-5'-phosphate (SAICAR), a metabolite abundant in proliferating cells, induces PKM2's protein kinase activity in vitro and in cells. Protein microarray experiments revealed that more than 100 human proteins, mostly protein kinases, are phosphorylated by PKM2-SAICAR. In particular, PKM2-SAICAR phosphorylates and activates Erk1/2, which in turn sensitizes PKM2 for SAICAR binding through phosphorylation. Additionally, PKM2-SAICAR was necessary to induce sustained Erk1/2 activation and mitogen-induced cell proliferation. Thus, the ligand-induced protein kinase activity from PKM2 is a mechanism that directly couples cell proliferation with intracellular metabolic status.
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